Method for forming a thin film of ultra-fine particles, and an apparatus for the same

ABSTRACT

An apparatus for forming a thin film of ultra-fine particles on a base body having a fine hole or a groove with a large aspect ratio (larger than one). The ultra-fine particles are smaller than 0.1 μm in diameter and are made from evaporated material. An aerosol is formed by dispersing and floating the ultra-fine particles in a gas at a pressure higher than 10 2  Pa in an aerosol-forming chamber. The base body is held by a holding mechanism within a thin-film forming container. A vacuum system is connected to the thin-film forming container. The aerosol-forming chamber is placed in communication with the thin-film forming container so that the aerosol is applied onto the inner wall surface of the fine hole or the groove. As a result, the ultra-fine particles are diffused and adsorbed onto the inner wall surface.

This application is a division of application Ser. No. 08/771,872 filedDec. 23, 1996 now U.S. Pat. No. 6,106,890.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relate to a method for forming a film of ultra-fineparticles, and an apparatus for the same, and more particularly to amethod for forming a film of ultra-fine particles and an apparatus forthe same by which a film of ultra-fine particle is formed on an innerwall surface of a hole smaller than 2 μm in diameter, and having anaspect ratio of larger than one.

2. Description of the Prior Art

Among methods for forming a thin film, there are a sputtering method, adeposition method, a physical vapor deposition method (PVD) such as anion-beam deposition method, a chemical deposition method (CVD), aplating method and any other liquid phase film-forming method. In thephysical vapor deposition method, atoms or molecules as film-formingmaterial move in a straight line, from the generating source.Accordingly, positions on the base body on which a thin film should beformed, depend on the geometrical arrangement or mechanical arrangementof the generating source of the film forming material and of the basebody. It is almost impossible to form a uniform film on an inner wallsurface of a fine hole of large aspect ratio or a groove of the similarsize, in the base body, since the straight flight line of the filmforming material does not reach there. On the other hand, it is possibleto form a relatively uniform film on the above fine hole or groove, bythe CVD method or liquid phase film forming method. However, it isunavoidable that any impurities are mixed into the formed thin film.

Among methods for forming thin films of ultra-fine particles, there area so-called “Gas Deposition method” or “Jet Printing method” in which atransport pipe and jet gas for transport are used to form locally a thinfilm, and “Cluster ion beam method” in which ionized grain beams areused. However, also in these methods, the film forming condition islimited by the geometrical or mechanical arrangement of the generatingsource of the film forming material and of the base body. Further, thereis the method in which ultra-fine particles are sinked or precipitatedfrom the liquid phase. However, in this method, a surface tension actsbetween the inner wall surface of the hole or groove, and so it isdifficult to form uniformly a thin film. Accordingly, this method cannotbe widely used.

As above described, it is difficult to form a uniform thin film withoutimpurity, on the inner wall surface of the fine hole or groove, by theabove Prior Art thin film forming methods. According, in one case, ahigh-integrated semiconductor device, in which via holes are aspectratio of larger than one, and a line width equal to a fraction of a μmor smaller is subjected to various limitation of manufacture itdifficult to form a uniform film of activated metal on the inner wallsurface of fine holes on a catalyst carrier of high performance.

As an example, a base body 5 in which fine holes or grooves are made, isschematically shown in FIG. 1. A film 2 of silicon oxidate as insulatoris formed on a silicon substrate 1. Another film 3 of aluminium isformed on the film 2. A fine groove 4 is formed in the film 2, and it isfilled with aluminium. A second silicon oxidate film 5 is formed on thealuminium film 3. A second groove 6 is made in the film 5, and itsbottom is the upper surface of the film 3. A via hole 7 with the bottomwhich is the upper surface of the film 3, is made in the groove 6. Thegroove 6 is 0.1 μm in width, and 0.3 μm in depth. The via hole 7 is 0.2μm in diameter, and 1 μm in depth. The aspect ratio of the groove 6 isequal to 3, and that of the via hole 7 is equal to 5. It is difficult toform a thin film of metal, or particularly, high-melting metal orceramics, onto the inner wall surfaces of the groove 6 and via hole 7,by the Prior Art CVD method.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a method offorming a thin film and an apparatus for the same in which a uniformthin film can be formed on an inner wall surface of a fine hole with adiameter of 2 μm or smaller in diameter, and having aspect ratio oflarger than one, or a groove of the similar size, regardless of anygeometrical or mechanical arrangement of a generating source of filmforming material, and of a base body to be film-formed, and in whichimpurity is not mixed into the thin film in contrast to the Prior ArtCVD method and liquid phase film forming method.

In accordance with an aspect of this invention,

A method of forming a thin film of ultra-fine particles comprising thesteps of: arranging a base under vacuum, said base body having a holewith bottom, a through hole, smaller than 2 μm in diameter and havingaspect rtio of larger than one, or a groove having the similar size;applying aerosol of ultra-fine particles of smaller than 0.1 μm indiameter onto an inner wall surface of said hole, said through hole orsaid groove, said aerosol dispersed and floating in gas under a pressurehigher than 10² Pa; and diffusing and adsorbing said aerosol onto saidinner wall surface.

In accordance with another aspect of this invention,

An apparatus for forming a film of ultra-fine particles comprising: anaerosol generating apparatus in which ultra-fine particles of smallerthan 0.1 μm in diameter are made from evaporated material, and aredispersed and floating in gas; a holding mechanism for holding a basebody having a hole with a bottom, or through hole, said hole or saidthrough hole formed through with a diameter smaller than 2 μm and anaspect ratio of larger than one; or a groove, a film of ultra-fineparticles being formed on said base body; a heating mechanism forheating said base body; a pressure-adjusting mechanism for maintainingsaid aerosol at a predetermined pressure; a thin-film forming containercontaining at least said holding mechanism; and a vacuum systemconnected to said film forming container;

The foregoing and other objects, features, and advantages of the presentinvention will be more readily understood upon consideration of thefollowing detailed description of the preferred embodiment of theinvention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged perspective view of a part of a base body havingfine holes and groove, as one example which is applied to the embodimentof this invention.

FIG. 2 is an enlarged perspective view of a part of the base body bywhich directions of thermal migration forces due to the thermal gradientare shown on the base body.

FIG. 3 is a schematic cross sectional view for explaining film formingof ultra-fine particles. A shows adsorption of ultra-fine particles atthe initial stage of the film forming and B shows micro-scopic view ofone adsorbed ultra-fine particle in the level of atom or molecule.

FIG. 4 is a schematic cross-sectional view for explaining film formingof ultra-fine particles. A shows a growing island-like film, B showsfurther growing film, more densed, and C shows microscopic view of oneadsorbed ultra-fine particle, chemically diffused in the inner wallsurface, on the level of

FIG. 5 is a schematic view of a film forming apparatus.

FIG. 6 is a schematic view of a aerosol-forming chamber.

FIG. 7 is a schematic side view showing a base body-holding mechanismfor holding plural base bodies, A shows a stationary type and B shows arotary type.

FIG. 8 is schematic plan views showing a series of plural film formingcontainers, A shows an inline-type, B shows a rotary type, C shows acluster type.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, the novel fluid mechanics of this invention, by which a thin filmcan be formed on an inner wall surface of a fine hole having a largeaspect ratio, by isotropic diffusion and adsorption will be described.

(1) Producing or forming aerosol in which ultra-fine particles aredispersed and floating in gas. For example, it can be produced in such amanner that film-forming material as solid ultra-fine particles areevaporated into gas as a dispersion medium.

(2) A base body having a fine hole or groove is cleaned and, as occasiondemands, it surface is activated. Then, the base body is held in afilm-forming container. For example, the base body is made of ceramics,and may be a three-dimensional body.

(3) The film-forming container is evacuated, so that the fine hole andgroove of the base body held in the film-forming container areevacuated.

(4) Aerosol in which ultra-fine particles are dispersed and floating ingas, is introduced into the film-forming container, to contact with thebase body and to invade, into the fine hole and groove.

(5) After a suitable time, an additional operation is applied to thebase body and then the base body on which the thin film of ultra-fineparticles has been formed, is taken out from the film forming container.

The thin film is basically formed on the base body in the above manner.The ultra-fine particles are isotropically diffused and the process ofthis invention is quasi-static. Accordingly, the principle of thisinvention is basically different from that of the gas deposition methodutilizing the dynamic energy of the carrying gas. This film-formingmethod is mechanically and macro-scopically similar to the oil-invadingmethod to a cable or the like. However, a film of a high melting metalor ceramic cannot be formed on the cable and oil cannot be invaded intothe cable.

(6) Additional opperations are effected as follows:

{circle around (1)} Thermal treatment;

Rising the temperature of the base body to activate ultra-fine particlesto be adsorbed on the inner wall surface.

(a) Surface Diffusion. This is a physical stabilization treatment.Typical temperature is 50 to 300° C.

Or (b) Adsorbing chemically ultra-fine particles onto the base. This isa chemical reacting treatment and a typical temperature is 200 to 800°C.

{circle around (2)} Surface Modification.

As occasion demands, after the thin-film forming container is evacuated,a reaction gas is introduced into the container to chemically react withthe surfaces of the ultra-fine particles and to clean and modifysurfaces of them. The typical gas reaction is hydrogenationnitrogenation, halogenation, oxidation or carbon adittion.

{circle around (3)} Multi-layer film forming;

Both in the heat treatment and in the surface modification treatment,film forming operations of different kinds of ultra-fine particles arerepeated.

{circle around (4)} Surface Protection;

Protecting gas or liquid is introduced into the container, for example,to protect the surfaces of ultra-fine particles and of the inner wallsurfaces on increasing the temperature.

Since heavy gas is not easily exited from the hole smaller than 0.1 μmin diameter, the protection for a short time can be possible.

In the principle of this invention, the thin film can be formed on theinner wall surface by diffusion and adsorption due to the isotropicfluid mechanism. The requirements for a fluid mechanics will now bedescribed as followings.

(1) In the thin film forming container of the usual size (for example,larger than 10 cm in diameter), the pressure of helium (He) should behigher than, for example, 260 Pa, or that of Argon (Ar) should be higherthan, for example, 130 Pa so that the ultra-fine particles of 5 nm ingrain size can float in the gas regardless of the gravity. The floatingof the ultra-fine particles can be obtained by the scattering movementdue to the collisions of the molecules or atoms of the gas, and theabove pressure is inversely proportional to the mean free path of theused gas. When the ultra-fine particles of 0.1 μm in diameter are stablyfloated, the pressure of the used gas should be higher than 10² Pa.

(2) The aerosol in which ultra-fine particles are dispersed andfloating, is invaded into the deep hole of 0.2 μm in diameter (forexample, aspect ratio of 5, and 1 μm in depth), and the ultra-fineparticles are uniformly distributed on the inner wall surface of thehole and adsorbed thereon. This requires the following:

(I) The ultra-fine particles do not coagulate by their collision in theaerosol.

(II) The adsorption or adhering of the ultra-fine particles due to theircollision with the inner wall surface is not localized near the entranceof the hole.

To fullfill the above requirement (I), a mean time required for thefirst collision of the ultra-fine particles to the collision of themshould be longer than a mean time required for the collision ofultra-fine fine particles to the inner wall surafce of the hole. Thefollowing formula (1) is required:

np·c·σ ² <a  (1)

where σ represents mean grain size of ultra-fine particles.

np represents grain density of ultra-fine particles

c represents volume of hole

a represents surface area of inner wall of the hole

To fullfill the above requirement (II), the following formula (2) isrequired:

λ/γ<l/5  (2)

r/l><V, >·(λ/λp,·u)  (3)

n p·c>a·β  (4)

n p<n g  (5)

(<V_(p)>/<V_(g)>)=(mg/mp_(1/2)  (6)

where λrepresents mean free path for the collision of the ultra-fineparticles and gas molecule or atom,

λp represents mean free path for the collision of the ultra-fineparticles each other

r represents of the hole

l represents depth of the hole number of the adsorbed particles to unitof the inner wall surface of the B hole and B represents

ng represents density of molecules or atoms of the gas

u represents speed of the invading of the aerosol of ultra-fineparticles dispersed and floating

Vp thermal motion speed of the ultra-fine particles

Vg represents thermal motion speed of the gas atoms or molecules

mp represents mass of ultra-fine particles

mg represents mass of gas atoms or molecules

In the formula (2), the aspect ratio of 5 is assumed.

The formula (3) of the equation 2 represents that the number of thetotal ultra-fine particles existing in the hole is larger than thenumber of the ultra-fine particles adsorbed on the inner wall surface ofthe hole in the time when the aerosol from the entrance of the holereaches the bottom of the hole.

Among the above described factors, r, x (therefore a and c), <Vp>,<Vg>are predetermined. The selective factors are σ, np, ng,u and β. λ and λpdepend on np,ng, α and the kind of the used gas.

In the requirements (I) and (II), there are five variables and fiveinequalities.

Actually, αand β are last determined. However, it is clear that thegrain size σ of the ultra-fine particles is smaller than 0.1 μm andfurther smaller than the diameter r of the hole. For example, the graindiameter σ<0.01 μm for the hole diameter r=0.2 μm is required.

When the hole diameter r is equal to 0.2 μm and the aspect ratio isequal to 5, and λ is smaller than 0.04 μm. When λ is equal to 0.04, thegas pressure is equal to 5 atm for Helium and to 1.5 atm for Argon. 1atom is equal to 10⁵ Pa (atmosphere pressure). When the hole diameter ris equal to 0.1 μm, the gas pressure is equal to 10 atm for Herium andto 3 atm for Argon, if the same relationship is assumed as in the abovecase. The smaller the hole diameter, the gas pressure the higher.

When the thin film formed on the inner wall surface of the hole consistsof more than one layer of atoms or molecules. β×[the number of atoms ormolecules constituting single ultra-fine particle] should be longer thanthe number of atoms or molecules per unit area in the single layer ofatoms or molecules. However, β is within the range limited by the aboverequirements (1) and (2). Accordingly, the value β cannot be alwayssatisfactorily selected. In such a case, the film forming operationsshould be repeated the required times. Further, when multilayers ofultra-fine particles of the same or different kinds are formed, the filmforming operations are repeated.

When there is no hindrance in the geometrical or mechanical arrangementof the generating source of film forming material and of the base body,a uniform film can be formed on the inner wall surface of the hole whichis large in diameter and the aspect ratio of which is about 5, also bythe prior art PVD method. Accordingly, either the prior art PVD methodor the method of this invention can be selected in consideration ofeconomy. However, when the hole diameter is smaller than about 2 μm, itis difficult to form uniformly a thin film by the prior art CVD method.In other words, that the hole diameter is smaller than 2 μm, is arequisite condition of this invention. Also when the hole diameter islarger than 2 μm, this invention can be applied. However, when the holediameter is larger than 2 μm, it is profittable to use the prior artmethod.

(3) When the ultra-fine particles are floated, the film thickness can becontrolled by the thermal migration method. This is one principle ofthis invention.

For example, the case will be discussed that the base body is so largeas to have the thermal gradient higher than 1° C. The dispersed andfloating ultra-fine particles are subject to the effect of the thermalmotion of the gas atoms or molecules. The ultra-fine particles are movedfrom the high temperature side to the low temperature side. Withreference to FIG. 2, the temperature of the upper surface S1 of the basebody S having the hole Sh is T1, that of the lower surface S2 of thebase body S, that of the gas G as disperse medium is Tg, the thermalmigration force is K1 on the upper surface S1, and that is K2 on thelower surface S2. Under the above conditions, K1 is equal to α (T1−Tg)and K2 is equal to α (T2−Tg). The ratio R1/R2 of the film forming R1 ofthe upper surface S1 to that R2 of the lower surface S2 is proportionalto (K2/K1). Accordingly, at the thermal gradient of T1>T2,KI>K2 and soR1<R2. The film forming speed R2 of the lower surface S2 is higher thanthat R1 of the upper surface S1. This effect is in the order ofmilli-seconds. This is practical in the quasi-static gas phase. Thus,the film forming speed on the inner wall surface of the fine hole can becontrolled with the thermal gradient or distribution on the base body.As above described, the thermal migration effect can be utilized inorder to obtain a uniform film or intentionally a predeterminedthickness difference of formed films.

In the above film forming operation, it is inferred that the atoms ormolecules of the ultra-fine particles difuse and spread on the innerwall surfaces of the film holes. This surface diffusion is not alwayseffected. Accordingly, additional treatments such as heat-treatment andintroductions of differrent gases, as occasion demands, are done tomodify the surfaces. FIG. 3 and FIG. 4 explain the film forming processand the effect of the heat treatment schematically. FIG. 3 A shows thephysical adsorption of the ultra-fine particles P onto the inner wallsurfaces of the fine hole Sh of the base body S at the initial stage.FIG. 3B shows microscopic view of atoms or molecules adsorbed on theinner wall surfaces. The inner wall surface is constituted by the blackcircles. One ultra-fine particle is constituted by the white circles.The black and white circles represent atoms or molecules.

Physically adsorbed ultra-fine particles P are heated, and so a part ofthe atoms or molecules constituting the ultra-fine particles P arescattered out and diffused onto the inner wall surface. They arecaptured by the atoms or molecules constituting the base body S to formnucleus. Such film forming operation is continued, and island-like filmsFi are formed on the inner wall surface of the hole Sh, as shown in FIG.4A.

Sequently, a close or uniform film F is formed. When the temperature ishigher, a part of the atoms or molecules constituting the ultra-fineparticles are diffused into the base body S and chemically adsorbed onthe inner wall surface. FIG. 4C corresponds to FIG. 3B, although theformer is more microscopic than the latter. One part g of the atoms ormolecules constituting the ultra-fine particle P are diffused onto theinner wall surface of the fine hole, while another part r there of arediffused into the base body S. As occasion demands, hydrogenation,oxidation, nitriding, hydrogenation or carbon addition for surfacemodification is added to the above heat treatment for the base body S.Or the above heat treatment and the above gas introduction may beemployed for clarifying the surface prior to the film forming, thesurface stabilization after the film forming, or activating.

Next, a thin film forming method for an ultra-fine particle and itsapparatus for the same, will be described with reference to thedrawings.

FIG. 5 is a schematic cross sectional view of a film forming apparatus10. It is of a pressure tight construction. Its film forming container11 is connected at the bottom to a vacuum system 12. A transport pipe 22is inserted into the film forming container 11. An aerosol whichultra-fine particles are dispersed and floating in gas, is transportedthrough the transport pipe 22 from an aerosol forming chamber 21. Acontrol valve 27 for controlling the supply of the aerosol is arrangedin the transport pipe 22 with a by-pass conduit 27 b with a valve.Further, a bottle 28 of the helium gas, as disperse medium is connectedthrough a control valve 29 to the aerosol forming chamber 21. Thecontrol valve 29 controls predetermined pressures of the aerosol formingchamber 21 and film forming container 11.

A first gas supply system 31 and a second gas supply system 33 areconnected through control valves 32, 34 to the film forming container11. A gas as occasion demands, is introduced for cleaning the base bodyS prior to film forming, or the surface modification and of the surfaceprotection before the heat treatment prior to the film forming for thestability and activation of the surface. In the embodiment of thisinvention, the first gas supply system 31 includes an ozone gas oroxygen radical generating apparatus for cleaning the base body S and thesecond gas supply system 33 includes an argon gas supply system for thestability processing after the film forming and the surface protection.

The film forming container 11 contains a base body holding frame 14 forholding the base body S as shown in FIG. 1. The base body S isintroduced into the film forming container 11 through not shown gate.The base body holding frame 14 contains a heating mechanism for heatingthe bas body S. And a film thickness monitor 15 as dummy is attachednear the base body S. The thickness of the thin film formed is measuredby a measuring control apparatus 16 which is fixed to a mounting flangearranged at the upper part of the film forming container 11. The filmthickness is optically measured by an ultraviolet radiation. Themeasuring control apparatus 16 further controls opening and closing ofthe control valves 27, 29 on the bases of the measuring result. A probe17 for measuring the film thickness is inserted into the film formingcontainer 11 above the film thickness monitor 15. The film thickness isoptically measured, but it may be measured electrically. The measuringcontrol apparatus 16 controls further the stop and start of the vacuumsystem 12 and opening and closing of a shutter for crucible 23 arrangedin the aerosol forming chamber 21, in FIG. 6.

FIG. 6 is a schematic cross sectional view of the above aerosol formingchamber 21. The crucible 23 is arranged in the aerosol forming chamber21. A not-shown shutter is arranged above the crucible 23. A highfrequency coil 25 is wound on the crucible 23 and the coil 25 isconnected electrically to a high frequency power source 24. Aluminum 26is contained in the crucible 23 and it is evaporated at thepredetermined temperature. The helium gas bottle 28, the control valve29 and the control valve 27 have been described as above.

The film forming apparatus 10 according to the embodiment of thisinvention is above constructed. Next, the film forming method will bedescribed using the above film forming apparatus 10.

First, the base body S is held on the base body holding frame 14 in thefilm forming container 11. The base body holding frame 14 is heated atthe 200° C. by the heating mechanism contained in the base body holdingframe 14. The interior of the film forming container 11 is evacuated bythe vacuum system 12. Sequently, the control valve 32 is opened for apredetermined time and ozone gas or the oxygen radical gas is introducedfrom the gas supply system 31. Accordingly, subtle amount of organicsadhearing to the base body S are oxygenatedly removed. At the same time,the groove 6 and the through hole 7 are evacuated. Sequently, thecontrol valve 27 is opened and the aerosol-forming chamber 21 isevacuated and then the vacuum system 12 stops. And the control valve 27is closed.

Next, the aerosol in which the ultra-fine particles are dispersing andfloating in the helium gas, are produced in the aerosol forming chamber21. The grain size of the ultra-fine particle almost depends on thetemperature of aluminum evaporating, the kind of the using gas and gaspressure. And referring to FIG. 6, control valve 29 is opened and heliumgas is introduced from the bottle 28 so that the pressure of the aerosolforming chamber 21 is maintained. At the same time, the aluminum 26 inthe crucible 23 is heated by the high frequency power source. Theshutter for the crucible is opened and aluminum 26 is evaporated. Theultra-fine particles are dispersed and floated in the helium gas.

Subsequently, the control valve 27 is opened. The ultra-fine particlesdispersed and floated in the helium gas are introduced into the filmforming container 11. After the pre-determined amount of aluminum isevaporated, the shutter for the crucible 23 is closed. The opening ofthe control valve 29 is controlled, and the pressures of the filmforming container 11 and the aerosol forming chamber 21 are risen andmaintained at the pressure of 5 atm. In this time, the aerosol isinvaded into the groove 6 and through hole 7 in the base body S. Theultra-fine particle of the aluminum are diffused to the heated groove 6and through hole 7.

Next, the film thicknesses aluminum formed on the inner surface of thegroove 6 and of the through hole 7 of the base body S, are in-directlymeasured by thickness monitor 15 on which the thin film is formed. Themeasuring control apparatus 16 evaporating, the kind of the using gasand gas pressure. And refering to FIG. 6, the control valve 29 is openedand helium gas is introduced from the bottle 28 so that the pressure ofthe aerosol forming chamber 21 is maintained at the pressure 260 Pa. Atthe same time, the aluminum 26 in the crucible 23 is heated by the highfrequency power source, to the temperature of 1100° C. The shutter forthe crucible 23 is opened and aluminum 26 is evaporated. The ultra fineparticle of mean grain size 5 nm are despersed and floated into thehelium gas.

Sequently, the control valve 27 is opened the ultra fine particlesdispersed and floated the heilum gas are introduced into the filmforming container 11. After the predetermined amount of aluminum isevaporated, the shutter for the crucible 23 is closed. The opening ofthe control valve 29 is controlled, and the pressures of the filmforming container 11 and the aerosol forming chamber 21 are risen andmaintained at the pressure of 5 atm. In this time, the aerosol isinvaded into the groove 6 and the through hole 7 in the base body S. Theultra fine particle of the aluminum are deffused to the heated groove 6and through

Next, the film thicknesses aluminum formed on the inner surface of thegroove 6 and of the through hole 7 of the base body S, are in-directlymeasured by thickness monitor 15 on which the thin film is formed. Themeasuring control apparatus 16 measures optically and continuously thefilm thickness formed on the monitor 15. When the predeterminedthickness of the film has been obtained, the control valves 27, 29 areclosed.

When the film thickness to be formed, is larger or when thepredetermined film thickness cannot be obtained by one aerosoloperation, the above operation except the cleaning operation, arerepeated. In the meantime, the measuring control apparatus 16 controlsthe opening and closing of valves 27, 29, the opening and closing of theshutter for the crucible 23 and the stop and start of the vacuum system12.

When the aluminum film of the predetermined thickness has been formed,the vacuum system 12 starts to evacuate the interior of the film formingcontainer 11. Then, the control valve 34 is opened to introduce argongas and the holding frame 14 is heated by the included heating mechanismto heat the base body S at the temperature of 300° C. The base body S isheated for the predetermined time. The aluminum film is stress-relaxedand stabilized with this heating operation. Thus, a series offilm-forming operations is completed. The base body S in which aluminumfilm is formed on the inner surface of the groove 6 and the through hole7, is taken out from the film forming container 11.

In the above embodiment, the aluminum ultra-fine particles of 5 nm inthe mean diameter are used for forming film on the inner surface walls.The width of the groove 6 is equal to 0.1 μm and that of the throughhole 7 is equal to 0.2 μm in diameter, and the groove 6 and the throughhole 7 have aspect ratios 3 and 5, respectively. The films are formed onthe inner walls of the above groove 6 and through hole 7. Further, whenthe aerosol is produced, the pressure 260 Pa is maintained and when thefilm is formed, its pressure is maintained at 5 atm. Thus, the pressuresare two-step wisely changed. However, when the hole is 2 μm in diameterand has the aspect ratio of one, the pressure of 10⁸-10⁴ Pa, can be usedin common, in the aerosol producing operation and the film formingoperation.

While the preferred embodiment has been described, variations there-towill occur to those skilled in the art within the scope of the presentinventive concepts which are delineated by the following claims.

For example, in the above embodiment, the one base body S is held on thebase body holding frame 14 in the film forming container 11. However, ofcourse, a plurality of base bodies S, as shown in FIG. 7A, may be heldon a base body holding frame 14′ and thin films may be formed on thebase bodies at the same time. Or as shown in FIG. 7B, a plurality of thebase bodies S′ may be arranged on the circumferential surfaces of theangular drum 18, in which the drum 18 is rotated around the axis.

In the above embodiment, the film forming apparatus 10 is constituted bythe one container 11. As described in FIG. 8, plural film formingcontainer 11 ₁, 11 ₂, - - - , 11 _(n) may be arranged through gatevalves. In this case, the base body S is in turn moved in the onedirection, to form multilayer form. A straight arrangement as shown inFIG. 8A may be used (inline type) or they may be arranged in circle asshown in FIG. 8B (rotary type). Further, a cluster type may be used. Inthis case, process chambers are arranged around a distribution center 11c. However, in all of the above described methods, a vacuum system, aaerosol producing chamber, a gas supply system, and a measuring controlapparatus are used every film containers 11 ₁, 11 ₂, - - - , 11 _(n).They are omitted in FIG. 8. Further, in all of the above methods, a basebody introducing and taking out chamber 11 ₀ is arranged for introducingthe base body or taking out the base body. In the inline type as shownin FIG. 8A, an introducing chamber 11 ₀′ is arranged at one end and ataking-out chamber 11 ₀″ is arranged at the other end. At this case, theintroducing chamber 11 ₀′ may be used as the cleaning chamber of thebase body S. In the rotary type as shown in FIG. 8B, the base body S ismoved in the direction as shown by the arrow m. The film containers 11₁, 11 ₂, - - - , 11 ₆ are rotatable in the direction as shown by thearrow n. Also, in the cluster type, they may be rotated around thedistribution center 11 c. A robot R which has retractable arm, isarranged in the distribution 11 c. Thus, the base body S is introducedinto the process chamber and taking out there from by the robot R.

Further, in the above embodiment, aluminum is evaporated by the highfrequency induction heating method in the aerosol forming chamber 21.Another method may be used. For example an electron beam heating method,a laser heating method and arc discharging method, can be employed.

Further, in the above embodiment, the vacuum system 12 is used in commonfor the film forming container 11 and the aerosol forming chamber 21.Instead, a vacuum system may be arranged exclusively for the aerosolforming chamber 21. Further, in the above embodiment, the control valve29 connected to the aerosol forming chamber 21 is used for the pressureholding, and pressure risening of the film forming container 11.However, the pressure control valve and gas bottle exclusively for thefilm forming container 11 may be used.

Further, the above described base body S has the through hole. It hasthe bottom as the upper surface of the lower layer. The through hole oflarger aspect ratio may be used in the embodiment.

In the above embodiment, the aluminum thin film is formed on the basebody S having the base plate 1 of silicon. However, a three-dimensionalcarrier of ceramics having fine holes may be applied. A catalyst such asmetal, for example, palladium may be formed on the inner wall surface ofthe fine holes of the catalyst carrier. Futher, when the surface isactivated after the film forming, the film forming method and the filmforming apparatus according to this invention can be applied to thecarrier.

Further, in the above embodiment, the film of the ultra-fine particle ofaluminum has been formed on the base body. However, another metal thanaluminum, such as gold, silver, copper and platinum may be used as thematerial of the ultra-fine particle. Further, ceramics as ultra-fineparticles, such as SiC (silicon carbide), TiN (titanium nitride), AlN(aluminum nitride), SiO₂ (oxygate silicon) and Al₂O₃ (alumina) may beused to form thin film. Further, in this embodiment, the helium gas isexemplified as the disperse medium of the ultra-fine particle. However,instead, argon gas, hydrogen gas, nitrogen gas, oxygen gas or mixture oftwo or three of them may be used.

What is claimed is:
 1. An apparatus for forming a film of ultra-fineparticles comprising: (A) an aerosol generating apparatus in whichultra-fine particles of smaller than 0.1 μm in diameter are made fromevaporated material, and are dispersed and floating in gas; (B) aholding mechanism for holding a base body having a hole with a bottom orthrough hole, said hole or said through hole formed therein with adiameter smaller than 2 μm and an aspect ratio of larger than one, or agroove formed therein with a width smaller than 2 μm and a ratio ofdepth/width larger than one, a film of ultra-fine particles being formedon said base body; (C) a heating mechanism for heating said base body;(D) a pressure-adjusting mechanism for maintaining said aerosol at apredetermined pressure; (E) a film forming container containing at leastsaid holding mechanism; and (F) a vacuum system connected to said filmforming container.
 2. An apparatus for forming a film of ultra-fineparticles according to claim 1, in which said heating mechanism is atleast one of a first heating source for imparting a temperaturedistribution or temperature gradient near said hold with a bottom, saidthrough hole or said groove in said base body, and a second heatingsource for activating said ultra-fine particles to be adsorbed onto theinner wall surface of said hole with a bottom, said through hole or saidgroove.
 3. An apparatus for forming a film of ultra-fine particlesaccording to claim 1, in which a introducing mechanism for introducinggas hydrogen, nitrogen, halogen and hydrocarbon to modify the surface ofultra-fine particles or said inner wall surface.
 4. An apparatus forforming a film of ultra-fine particles according to claim 1 in which ameasurement control apparatus is arranged for measuring continuously thethickness of formed film of ultra-fine particles, control the start andstop of aerosol introduction, on the basis of the measurement result andcontrol said pressure-adjusting mechanism.
 5. An apparatus for forming afilm of ultra-fine particles according to claim 1 in which a secondintroducing mechanism is arranged for introducing a protecting gas orprotecting liquid to protect said film of ultra-fine particles.
 6. Anapparatus for forming a film of ultra-fine particles according to claim1 in which said holding mechanism holds a plurality of said base bodies.7. An apparatus for forming a film of ultra-fine particles according toclaim 1 in which a plurality of said film forming containers arearranged in a straight line (in-line type) or in a circle (rotary type)or in a cluster, or they are arranged radially around a distributingcenter of said base bodies.
 8. An apparatus for forming a film ofultra-fine particles according to claim 2, in which a introducingmechanism for introducing gas hydrogen, nitrogen, halogen andhydrocarbon to modify the surface of ultra-fine particles or said innerwall surface.